INTRODUCTION: Rhythmic Gymnastics (RG) is a type of gymnastics
that requires a high degree of flexibility due to the complexity of the
required movements. OBJECTIVE: this
study aimed to compare the sit and reach test (SRT) and the Biophotogrammetry
technique as indicators of trunk flexibility in beginning GR practitioners. METHODS: the sample included 60
girls (5-11 years old) from a universe of 110, all enrolled in a Center for
Sports Initiation in Parana State. Data collection was performed in November, 2009.
In order to compare the SRT and biophotogrammetry, angles of the pelvis (PW),
spinal flexion (SW) and total trunk flexion (TW) were drawn. RESULTS: the average score achieved by the
participants on the SRT scale was 27.75 cm. A strong correlation was found
between TW angle and the SRT values. Since it is a combination of the SW and
PW, the TW provides a global view of the distance from the trunk to the legs
when bending occurs during the test. Therefore, the correlations between the
angles are good and meaningful. CONCLUSION: since
the SRT has some intervening factors that may mask the result,
biophotogrammetry is discussed as a test that allows the observation of
reliable data for measuring flexibility and muscle compensation which are not
usually identified, through photographs and angular calculations.

Keywords: angles, sit and reach test,
biophotogrammetry

INTRODUCTION

Flexibility has considerable participation and contribution in
many sports modalities; however, its role especially intensifies in sports
which involve aesthetical content of the perfect body figure, acting as
morphofunctional priority of the locomotor system1.

According to Dupont2, rhythmic gymnastics (RG) is a
sport in which the range of motion predicts the quality and the value of difficulty
of its performance. Flexibility is the factor which is the most demanded at the
competition level, since the punctuation code itself categorically requests
this physical valence, leading to an extreme demand.

Thus, in this context, it is observed that controlling the
level of flexibility is a crucial control factor, and that the sit and reach
test (SRT) is among the most frequently used methods in flexibility
evaluations. The SRT is an indirect method which enables intra and
inter-subject comparisons, characterized as a test of easy performance and high
practicality3.

According to Baltaci et al.4, the SRT is present in many
batteries which evaluate physical fitness, since it is believed that keeping
the low back and hamstrings flexibility level suitable may substantially avoid
acute and chronic osteomuscular injuries, besides low back problems, posture
swerves and gait limitations.

However, Cardoso et al.5 comment that some factors may alter the test result such as
disparity of proportion in the length of lower limbs compared to upper limbs,
spine mobility and scapular abduction. Such components act as potential
interference, since an individual may receive a high classification in the test
even if he/she does not present appropriate flexibility.

Moreover, Chagas and Bhering6 highlight
that a high level of shoulder protrusion and of thoracic spine flexion may act
as factors which alter the validity of the measures of the test under
consideration, since under these conditions, the movement performance would be
facilitated. However, it would not evaluate the real condition of the subject
and would doubt the result of what really is wanted to be evaluated.

Some evaluators, especially in the
physiotherapy field, use the kinemetry for
evaluation of movements in physical valences such as flexibility and movement
velocity. In that process, cameras, camcorders and specific calculation
programs which capture the image and enable their careful observation as well
as comparison with other images are used5.

Based on this context and considering the SRT
intervenient factors, one of the ways of also evaluating this physical
component would be through biophotogrammetry, designated as an instrument of
metric application in images which record human movements with high reliability7.

More specifically, biophotogrammetry came
about in the instrument context to be used in the biomechanical analysis as a
bidimensional (2D) photogrammetry variable, which gives priority and tries to
solve the difficulties of the body movement analysis in the environments where
the professional practice aimed at health is typical. Such priority gave
opportunity to the onset of suppositions which guided a systematized treatment
in the image and its measurement7.

Thus, the aim of this study was to compare
the sit and reach test (SRT) and the biophotogrammetry technique as indicators
of trunk flexibility in beginning participants of RG.

METHODOLOGY

This study was descriptive, observational and
transversal for the images analysis. 60 female children
(which corresponded to 54.5% of the universe), aged between five and 11 years
were evaluated in the study. They were enrolled in a
project of sport initiation in rhythmic gymnastics in Paraná state and
presented the Free and Clarified Consent Form signed by their parents or legal
tutors. Data collection occurred in November, 2009 and the sample was
stratified in three groups: younger than seven years old (12 girls), from seven
to nine years old (37 girls) and older than nine years old (11 girls).

The instruments for data collection were a
Sony® digital camera of 10 megapixels of resolution, a measuring tape, adhesive tape and Pimaco® spheric and white surface adhesive markers of 13 millimeters of
diameter. The evaluation method used was the biophotogrammetry, which consisted
in a systematized process which analyzes in 2D, in which its steps and conduct
are manually performed so that a representation of quantitative factors of a
body movement is performed. Its main goal is to offer in numerical expression
the meanings of movements which help in the data interpretation7.

Concerning the initial posture for the SRT
evaluation with bench, the child should sit in front of the bench so that the
plantar region of her feet was completely rested on the wall, legs should be
extended, trunk erect and fingertips of both hands touching the movable device
on the bench next to the marking. The child should afterwards push the movable
device with the fingertips the most as possible without touching twice or
making a sudden move. The evaluator should rest hands on the child's knees in
order to keep them extended during the entire test6-8.

The standard bench used for the test
consisted of a wooden box measuring 30.5cm x 30.5cm x 50.6cm. On the top of it
there is a metric scale of 50 centimeters with a sliding movable device which
let determine the reach of the child9.

The images collected for analysis were of the
initial and final positions of the SRT, in three trials (all photographed).

The delimitation of strategic anatomic points
which enabled the measurement of angles was necessary so that this test could
be analyzed through the image. The bilateral points determined were: last
fluctuating rib (lateral view), antero-superior iliac spine, trochanter of the
femur, lateral condyle of the femur and lateral malleolus.

These points were marked on the children by
palpatory anatomy. The palpatory anatomy consists of an exploration and
examination process through touch. It is used by many health professionals to
help in the clinical diagnosis and treatment10.

After the photos have been taken, they were
imported to the CorelDraw computer program, version 12, which has instruments which permit
the measurements of angles between markers, which resulted in a subsequent
analysis, the results concerning the flexibility movements.

In the SRT there was the construction of
three angles on the image, both at the initial and final positions. The first
angle was named SW (low back spine flexion), which started on the last rib
until the antero-superior iliac spine. The second angle was named PW (pelvis
flexion), which started in the antero-superior iliac spine and ended in the
trochanter. The third angle named TW (total trunk flexion), started on the last
rib and followed until the trochanter (figures 1 and 2).

The evaluation process occurred at the time
of the children's school and while a group of children was evaluated, the other
girls continued having classes. Thus, a group of approximately five girls at a
time was called, the girls wore the appropriate garment, and the evaluator
placed the markers on the determined bone segments by palpatory anatomy and
asked the child to perform the SRT and repeated it three times. A photo was
taken at every movement and the initial preparation for the test performance
was also photographed.

The distance between the child and the camera
was measured with the measuring tape and marked on the ground with adhesive
tape at a length which let that the image of the entire body of the child could
be focused on the camera. Thus, this marking on the ground was used to
photograph all the children so that a standard for the images could be kept.

The values of each angle and of each
numerical result derived from the tests were transferred to a table of the SPSS 15.0 program which generated some statistical tests in order to
collide results.

Among the tests, we can mention the frequency
distribution of the variables which calculated means and standard deviations.
Additionally, the Kolmogorov-Smirnov test was also performed to verify the
normality of the sample and allow the application of the Pearson correlation,
which measured the level of correlation between the two inferential variables
of metric scale11.

The present study met all the requirements of
the Resolution 196/96 of the National Health Board and had its protocol
approved in the Ethics in Research Committee of the UFPR under the number
1013.138.10.09 and CAAE 0082.0.091.000-10.

RESULTS

The profile of the studied children can be
observed in table 1. In the sit and reach test (SRT), the sample obtained mean
result of 27.75 centimeters.

The angular data presented normal
distribution and according to table 2, since the SRT and stature negatively
correlated (r = 0.283), it can be inferred that the shorter girls presented
better results.

The strong negative between angles and
SRT suggests that the higher the value reached in the SRT the lower the angular
values. The angle which best related to the SRT was the TW. However, for the
same TW values, different SW and PW compositions were found, which specifically evaluate low back spine flexion and pelvis flexion, respectively,
as presented in table 3.

In table 4 the
correlation between the angular variables and the SRT are found for the
different age groups studied (group 1: five to seven years; group 2: eight and
nine years; and group 3: 10 and 11 years).

In group 1 strong correlation between TW with
SW and with the SRT was observed. In group 2, it was observed that the TW and
SW relation and with PW follows the same pattern from group 1; however, its
relation with SRT changes to a light correlation, which related with PW and SW
is not significant anymore. Group 3 presented moderate correlation of TW with
SW and SRT; however, the relation with PW differently from the other groups, ends up being the highest of all.

Thus, both in
the global and stratified per ages analyses the SRT bettr correlated with the
SW (spine) than with the PW (pelvis).

DISCUSSION

Concerning the anthropometric profile of the
children, the study demonstrated that the mean value reached by the sample in
the SRT is above the Physical
Best12,
suggested proposal, in which it is established that the child should reach a
minimum of 25 centimeters in the test.

The evaluated children are also in agreement
with the standard determined by the reference tables of the FITNESSGRAM13, in which, for the female sex, the
values comprehended between 23 and 28 centimeters indicate a healthy zone of
physical fitness (ZSApF).

In the study by Venturi et al.14, the flexibility of 22 girls aged
between six and 10 years and practitioners for one year of classical ballet and
educational dance, was evaluated with the SRT. In the results, the girls who
practiced ballet reached mean of 28.82cm, and the girls who practiced
educational dance reached 21.55cm in the test.

When confronting the mentioned study with the
results of the SRT of the present study (27.75cm), it can be observed that the
results obtained by the girls who practiced ballet are similar. Probably, this
can be explained by the vast use of flexibility from both ballet and RG15.

On the other
hand, in another study conducted with 87 students, aged between six and 17
years, divided in two groups (six to 12 years and 13 to 17 years), the mean of
the SRT of the younger girls was 15.4cm and the mean of the older girls was
16.1cm, results much below than the ones found in the assessed sample16.

Moreover, it was observed in the results of
the present study that the younger girls obtained better result in the SRT. In
a study carried out with 420 children and adolescents from seven to 17 years
old from both genders, it was observed that flexibility points out tendency to
decrease in the results with age progression and, when sexes are compared, the
female sex presents better results17.

Due to the negative correlation of the angles
with the SRT, it was observed that the higher the value reached in the SRT the
lower the angle values. It is believed that the correlation was not even higher
due to the fact that in girls with hamstring shortening, with restriction of
pelvic movement, there was a compensation with the low back spine, since when
the hamstrings are shortened, the pelvis cannot perform anteroversion and
consequently, the low back spine increases curvature to compensate for the
performance of the required movement, causing the angles not to present a
homogeneous variation among subjects with the same SRT value (table 3).

The explanation of the pelvic behavior is in
agreement with Alter18, who states that when an anterior pelvic
inclination is performed, the ischial tuberosity (origin of the hamstring) is
placed at a superior position and later more distant from the proximal and
fibular tibial insertions of the hamstrings, causing the musculature to be more
elongated. However, if the individual performs a compensation pelvic movement,
it is said that this fact occurred due to the combined flexion patterns of the
cervical, thoracic and lumbar spine, which follow a concept based on the
"lumbar-pelvic rhythm" behavior19. In other words, since the pelvis
posteriorly rotates to follow the dorsal curvature, the ischial tuberosity ends
up anterior and lowly dislocating, placing the origin of the muscle closer to
its insertion.

It is natural for the body to try to
compensate for the increased tension on the hamstrings, taking a back
positioning which results in less musculo-tendinous tension. Thus, it is
understood that the dorsal rounding is a trial to dribble the movement and reach
further with the hands, since, using such strategy, the spine will not need to
perform too many linear or angular dislocations, requiring less range of
motion. Besides that, the cumulative flexions which occur along all vertebrae
may create an illusion of high stretching level of the hamstrings18.

In the study by Cardoso et al.5, an angle similar to the PW was used
to evaluate the stretching of the hamstring muscles. According to the authors,
in the sit and reach test only the reach of the fingers at the most distant
point , rather than the angle made by the hip joint is considered, which may
predict with more accuracy the length of the hamstrings.

Thus, to consider only the reach of the
fingers in the SRT may mask some intervenient factors such as differences in
proportion between lower and upper limbs, spine mobility and reach3,20,21.

In this study strong correlation of the TW
angle and the SRT was observed. This angle ends up being a composition of the
SW and the PW, enabling a global visualization of the trunk distance until the
lower limbs when it performs the flexion the test requires. Therefore, the
correlations of the TW and SW and TW and PW are good and significant.

The research by Cardoso et al.5, as well as the present study used
the angular kinemetry with the SRT; for that reason, it built a reference angle
of the pelvic region made of the anatomic points antero-superior iliac crest
and trochanter major. In their results, high intra and inter-observer
reliability was found.

In the study by Miñarro et al.3, to compare the SRT validity with a modified version, the back-saver sit-and-reach (BS), in which one of the legs should be extended while the other
is flexed during the test performance, the thoracic spine lumbar spine and
pelvis angles measured by an inclinometer were used as a criterion test. The
low correlation of the BS evidenced that the SRT reached better validity when
correlated with the criterion test, besides being of easier application and
performance.

In another study, the SRT, the BS, another
modified version named modified
sit-and-reach test (MSR), in which the reach is
controlled and the toe
touch test (TT), which is performed by the standing
trunk flexion are compared. The criterion test used was the passive straight leg raise
test, in which the leg is passively raised and the
angulation formed is measured by an inclinometer. All tests had moderate
validity to estimate flexibility of the hamstrings; however, the authors
recommend that doctors, physiotherapists and researchers adopt an angular test
for measurement of the muscular length22.

The SW angle suffered influence of the
stature, which is biomechanically explainable, since during growth the trunk
increases its size longitudinally, causing the spatial disposition of the
markers to be more distant in taller children, consequently leading to higher
angle value.

According to Haywood and Getchell23,
in the relative growth, the legs grow faster than the trunk and the head in the
first and second childhoods. Afterwards, in adolescence, there is the growth
spurt, in which there is mainly increase of the trunk up to the adulthood.

Flexibility of the hip and spine joints is an
important attribute for the RG practice. The current punctuation code
establishes in the routine compositions, 10 movements of higher complexity,
which require from the gymnast high articular amplitude and high level of
flexibility2,24.

However, since flexibility is specific in
each region, it is difficult to accurately measure and evaluate flexibility in
general25. Nevertheless, some specialists recommend that the
flexibility measurement of the low region of the back, hip and of the
hamstrings should be included in the evaluation protocols. When these regions
present low levels of flexibility biomechanical alterations which induce to
patellofemoral dysfunction, low back pain, athletic pubalgia, tendinitis and
posture swerves may occur5,22,26-28.

Liemhon29 observed that there is
low performance in this test due to the compensation between the muscular
groups which generate rounding of the upper dorsal region. It was also verified
that there may be compensation due to extreme flexibility of the lumbar region
which reflects in a satisfactory score in the test, as found in the present
study.

Thus, in this study the biophotogrammetry was
able to accurately evaluate the body segments which presented movement
restriction or good mobility, facilitating the identification of compensations
during the SRT performance.

CONCLUSION

Although the SRT is a test widely used in
evaluation batteries, it has been demonstrated that it ends up producing
non-reliable data, since there are many components which corroborate to the
inaccuracy of the test. Thus, the biophotogrammetry, joined with the SRT,
provides reliable data for the measurement of the stretching of the hamstring
and paravertebral muscles, specifically, as well as the trunk anterior flexion
at a global level.

It also enables
a longitudinal follow-up, since the images show with property the test
performance manner, as well as the possible compensations, making it possible
to visualize the athletes' evolution in continuous evaluations. Additionally,
it allows suitable training prescription since those athletes who present lower flexibility perform different exercises from those who present
higher flexibility, with the purpose to prevent injuries by unfavorable
training loads.